model: fix boundary in bpe

0x007e is a tilde and was getting adjusted (+0x00a2) to 0x0120 in the
encode, but then in the decode it was getting adjusted down (-0x0100) to
0x0020. The boundary for the +0x00a2 case has been adjusted to fix this

Fixes: #11966

model/bytepairencoding.go

@@ -109,7 +109,7 @@ func (bpe BytePairEncoding) Encode(s string, addSpecial bool) ([]int32, error) {
 					r = 0x0143
 				case r <= 0x0020:
 					r = r + 0x0100
-				case r >= 0x007e && r <= 0x00a0:
+				case r >= 0x007f && r <= 0x00a0:
 					r = r + 0x00a2
 				}